468 / 2019-02-27 14:46:14

Exogenous expression of intronic long non-coding RNAs facilitates transcriptional activation of host genes by repressing histone H3K27 trimethylation

intron,H3K27me3,FLC,long non-coding RNA,flowering time

全体主题 > RNA Biology

In Arabidopsis, an lncRNA, named COLDAIR, is from the first intron of Flowering Locus C (FLC), a key flowering repressor. Here, we found that exogenous over-expression of a foreign COLDAIR sequence in Arabidopsis plants could significantly enhance the FLC expression in trans in a subset of the transformed lines and thereby delayed flowering time. In the wild-type plants, the FLC genic region was enriched with a high level of the repressive histone H3K27me3, which led to a low expression level of FLC. In the plants transformed with the construct over-expressing COLDAIR, the H3K27me3 level was reduced and the expression of FLC was accordingly activated, suggesting that the exogenous over-expression of COLDAIR represses H3K27me3 and thereby activates the FLC expression. Furthermore, we identified a mutant defective in a RNA recognition motif (RRM)-containing protein by screening for suppressors of the late-flowering COLDAIR-transformed plants. In the mutant plants, the H3K27me3 and expression levels of FLC were restored to the levels as in the non-transformed plants, leading to an early flowering of the mutant plants. Together, these results reveal how the H3K27me3 and expression levels of H3K27me3-enriched genes are regulated by exogenous expression of intronic lncRNAs in trans in Arabidopsis. Considering that intronic lncRNAs are ubiquitously observed in various eukaryotes, we predict that the mechanism is mostly likely to be conserved from plants to other eukaryotes.